Diagnosing cable faults within a network

ABSTRACT

Various embodiments relate to detecting a cable fault within a network. A method may include transmitting a pulse signal to a cable of a shared bus from a node, and observing a signal received at the node in response to the pulse signal. The method may also include determining a fault condition of the cable based on the pulse signal and on an amplitude of each sample of a number of samples of the one or more observed signals.

PRIORITY CLAIM

This application is a continuation of U.S. patent application Ser. No.16/588,714, filed Sep. 30, 2019, now U.S. Pat. No. 11,121,782, issuedSep. 14, 2021, which claims the benefit of the filing date of ChineseProvisional Patent Application Serial No. 201910784058.2, filed Aug. 23,2019, for “DIAGNOSING CABLE FAULTS WITHIN A NETWORK.”

TECHNICAL FIELD

The present disclosure relates generally to data communication networks,and more specifically, to diagnosing cable faults within a local areanetwork. Yet more specifically, various embodiments of the disclosurerelate to diagnosing cable faults within a single pair Ethernet networkvia time-domain reflectometry.

BACKGROUND

Various interface standards for connecting computers and externalperipherals may be used to provide connectivity at high speeds. A widelyused, flexible networking standard for connecting computers (e.g., inLocal Area Networks (LANs) and Wide Area Networks (WANs)) is theEthernet protocol. Ethernet communication generally refers topoint-to-point communication within a network of multiple end points.Ethernet generally makes efficient use of shared resources, is easy tomaintain and reconfigure, and is compatible across many systems.

BRIEF DESCRIPTION OF THE DRAWINGS

While this disclosure concludes with claims particularly pointing outand distinctly claiming specific embodiments, various features andadvantages of embodiments within the scope of this disclosure may bemore readily ascertained from the following description when read inconjunction with the accompanying drawings, in which:

FIG. 1 depicts a network including a number of nodes, in accordance withvarious embodiments of the disclosure;

FIG. 2 illustrates a node, including a media access layer and a physicallayer, coupled to a network, according to various embodiments of thedisclosure;

FIG. 3A shows a timing diagram depicting a transmit pulse signal, areflection signal, and an observed signal;

FIG. 3B shows another timing diagram depicting a transmit pulse signal,a reflection signal, and an observed signal;

FIG. 3C shows another timing diagram depicting a transmit pulse signaland an observed signal;

FIG. 4A shows a timing diagram depicting a transmit pulse signal, areflection signal, an observed signal, and a signal states for a numberof sampling times;

FIG. 4B shows another timing diagram depicting a transmit pulse signal,a reflection signal, an observed signal, and signal states for a numberof sampling times;

FIG. 5 illustrates an example physical layer of a node of a network,according to various embodiments of the disclosure;

FIG. 6 illustrates a signal detector, according to various embodimentsof the disclosure; and

FIG. 7 is a flowchart of an example method of detecting cable faults ina network.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof, and in which are shown,by way of illustration, specific examples of embodiments in which thepresent disclosure may be practiced. These embodiments are described insufficient detail to enable a person of ordinary skill in the art topractice the present disclosure. However, other embodiments may beutilized, and structural, material, and process changes may be madewithout departing from the scope of the disclosure.

The illustrations presented herein are not meant to be actual views ofany particular method, system, device, or structure, but are merelyidealized representations that are employed to describe the embodimentsof the present disclosure. The drawings presented herein are notnecessarily drawn to scale. Similar structures or components in thevarious drawings may retain the same or similar numbering for theconvenience of the reader; however, the similarity in numbering does notmean that the structures or components are necessarily identical insize, composition, configuration, or any other property.

The following description may include examples to help enable one ofordinary skill in the art to practice the disclosed embodiments. The useof the terms “exemplary,” “by example,” and “for example,” means thatthe related description is explanatory, and though the scope of thedisclosure is intended to encompass the examples and legal equivalents,the use of such terms is not intended to limit the scope of anembodiment or this disclosure to the specified components, steps,features, functions, or the like.

It will be readily understood that the components of the embodiments asgenerally described herein and illustrated in the drawing could bearranged and designed in a wide variety of different configurations.Thus, the following description of various embodiments is not intendedto limit the scope of the present disclosure, but is merelyrepresentative of various embodiments. While the various aspects of theembodiments may be presented in drawings, the drawings are notnecessarily drawn to scale unless specifically indicated.

Furthermore, specific implementations shown and described are onlyexamples and should not be construed as the only way to implement thepresent disclosure unless specified otherwise herein. Elements,circuits, and functions may be shown in block diagram form in order notto obscure the present disclosure in unnecessary detail. Conversely,specific implementations shown and described are exemplary only andshould not be construed as the only way to implement the presentdisclosure unless specified otherwise herein. Additionally, blockdefinitions and partitioning of logic between various blocks isexemplary of a specific implementation. It will be readily apparent toone of ordinary skill in the art that the present disclosure may bepracticed by numerous other partitioning solutions. For the most part,details concerning timing considerations and the like have been omittedwhere such details are not necessary to obtain a complete understandingof the present disclosure and are within the abilities of persons ofordinary skill in the relevant art.

Those of ordinary skill in the art would understand that information andsignals may be represented using any of a variety of differenttechnologies and techniques. Some drawings may illustrate signals as asingle signal for clarity of presentation and description. It will beunderstood by a person of ordinary skill in the art that the signal mayrepresent a bus of signals, wherein the bus may have a variety of bitwidths and the present disclosure may be implemented on any number ofdata signals including a single data signal.

The various illustrative logical blocks, modules, and circuits describedin connection with the embodiments disclosed herein may be implementedor performed with a general purpose processor, a special purposeprocessor, a Digital Signal Processor (DSP), an Integrated Circuit (IC),an Application Specific Integrated Circuit (ASIC), a Field ProgrammableGate Array (FPGA) or other programmable logic device, discrete gate ortransistor logic, discrete hardware components, or any combinationthereof designed to perform the functions described herein. Ageneral-purpose processor (may also be referred to herein as a hostprocessor or simply a host) may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, such as a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration. A general-purpose computer including a processor isconsidered a special-purpose computer while the general-purpose computeris configured to execute computing instructions (e.g., software code)related to embodiments of the present disclosure.

The embodiments may be described in terms of a process that is depictedas a flowchart, a flow diagram, a structure diagram, or a block diagram.Although a flowchart may describe operational acts as a sequentialprocess, many of these acts can be performed in another sequence, inparallel, or substantially concurrently. In addition, the order of theacts may be re-arranged. A process may correspond to a method, a thread,a function, a procedure, a subroutine, a subprogram, etc. Furthermore,the methods disclosed herein may be implemented in hardware, software,or both. If implemented in software, the functions may be stored ortransmitted as one or more instructions or code on computer-readablemedia. Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another.

Any reference to an element herein using a designation such as “first,”“second,” and so forth does not limit the quantity or order of thoseelements, unless such limitation is explicitly stated. Rather, thesedesignations may be used herein as a convenient method of distinguishingbetween two or more elements or instances of an element. Thus, areference to first and second elements does not mean that only twoelements may be employed there or that the first element must precedethe second element in some manner. In addition, unless stated otherwise,a set of elements may comprise one or more elements.

As used herein, the term “substantially” in reference to a givenparameter, property, or condition means and includes to a degree thatone of ordinary skill in the art would understand that the givenparameter, property, or condition is met with a small degree ofvariance, such as, for example, within acceptable manufacturingtolerances. By way of example, depending on the particular parameter,property, or condition that is substantially met, the parameter,property, or condition may be at least 90% met, at least 95% met, oreven at least 99% met.

A vehicle, such as an automobile, a truck, a bus, a ship, and/or anaircraft, may include a vehicle communication network. The complexity ofa vehicle communication network may vary depending on a number ofelectronic devices within the network. For example, an advanced vehiclecommunication network may include various control modules for, forexample, engine control, transmission control, safety control (e.g.,antilock braking), and emissions control. To support these modules, theautomotive industry relies on various communication protocols.

10SPE (i.e., 10 Mbps Single Pair Ethernet) is network technologyspecification currently under development by the Institute of Electricaland Electronics Engineers as specification IEEE 802.3cg™. A 10SPEphysical layer (PHY) may operate in a half-duplex mode and may supportcarrier-sense multiple access with collision detection (CSMA/CD), whichis a media access control method used most notably in early Ethernettechnology for local area networking.

Cable fault diagnosis is necessary for various applications, such as invehicle communication networks utilizing 10SPE. However, 10SPE does notdefine cable fault diagnosis.

Various embodiments relate to detecting cable fault types, includingcable “open” and cable “short” faults, based on time domain reflection.More specifically, various embodiments relate to detecting, and possiblydiagnosing, cable faults in a 10SPE network. Yet more specifically,various embodiments relate to a 10SPE physical layer (PHY) configured todetect cable fault types (e.g., cable open, cable short, normal,mismatch) of an associated 10SPE network based on time domain reflection(TDR).

In some embodiments, a 10SPE PHY may include detection circuitry (e.g.,including a signal detector with a programmable threshold value)configured for detecting, and possibly diagnosing, cable faults in a10SPE network. According to some embodiments, as described more fullybelow, during a contemplated operation, a pulse may be transmitted froma PHY, and if a reflection is not detected at the PHY, it may bedetermined that no cable fault exists (e.g., a cable diagnosis of“normal”). However, if a reflection is detected at the PHY, it may bedetermined that a cable fault exists. Further, based on the detectedreflection (e.g., a phase and/or an orientation (positive or negative)),a type of cable fault may be determined. More specifically, if thedetected reflection includes a shape that is similar to a shape of thetransmitted pulse, it may be determined that an “open” fault exists. Ifthe detected reflection includes a shape that is similar to, butopposite of, the transmitted pulse, it may be determined that a “short”fault exits. Further, if the detected reflection includes an amplitudethat is different than an amplitude of the transmitted pulse, it may bedetermined that a “mismatch” fault exists. More specifically, if thedetected reflection includes a shape that is similar to a shape of thetransmitted pulse, and the reflection and the transmitted pulse havedifferent amplitudes, it may be determined that an “open mismatch” faultexists. Further, if the detected reflection includes a shape that issimilar to, but opposite of, the transmitted pulse, and the reflectionand the transmitted pulse have different amplitudes, it may bedetermined that a “short mismatch” fault exits.

According to a more specific example described more fully below, asignal detector of a PHY may be configured with a first threshold value(e.g., a high threshold value), and the PHY may transmit a first pulsevia a cable that is coupled to a network (e.g., 10 SPE network). Forexample, the first pulse may be a positive pulse, a negative pulse, or adifferential pulse. For example, the first threshold value may bebetween 1× and 2×, wherein X is an amplitude of the first pulse.Further, a first signal, received in response to the first pulse, may beobserved at the PHY. Furthermore, a state (also referred to herein as a“value”) of the first signal at each sampling time of a number ofsampling times of the first signal may be determined (i.e., based on acomparison to the first threshold value), and possibly recorded.

Continuing with this specific example, the signal detector may beconfigured with at least one other threshold value (e.g., a mediumthreshold value and/or a negative threshold value), and at least otherpulse may be transmitted via the cable. Further, at least one othersignal, received in response to the second pulse, may be observed at thePHY. Furthermore, a state of the at least one other signal at eachsampling time of a number of sampling times of the at least one othersignal may be determined (i.e., based on a comparison to the at leastone other threshold value).

More specifically, the signal detector may be configured with a secondthreshold value (e.g., a medium threshold value), and a second pulse maybe transmitted via the cable. For example, the second pulse besubstantially similar to the first pulse (e.g., same shape, amplitude,and duration). Further, for example, the second threshold value may bebetween 0 and X, wherein X is an amplitude of the second pulse. Further,a second signal, received in response to the second pulse, may beobserved at the PHY. Furthermore, a state of the second signal at eachsampling time of a number of sampling times of the second signal may bedetermined (i.e., based on a comparison to the second threshold value),and possibly recorded.

Continuing with this specific example, the signal detector may beconfigured with a third threshold value (e.g., a negative thresholdvalue), and a third pulse may be transmitted via the cable. For example,the third pulse be substantially similar to the first pulse and thesecond pules (e.g., same shape, amplitude, and duration). Further, forexample, the third threshold value may be between 0 and —X, wherein X isan amplitude of the third pulse. Further, a third signal, received inresponse to the second pulse, may be observed at the PHY. Furthermore, astate of the third signal at each sampling time of a number of samplingtimes of the third signal may be determined (i.e., based on a comparisonto the third threshold value), and possibly recorded.

Continuing with this specific example, as described more fully below, areflection signal may be determined based on a transmitted pulse (e.g.,the first pulse, the second pulse, or the third pulse) and a state ofeach observed signal (e.g., the first, second, and third observedsignals) at each sampling time of a number of sampling times of observedsignals. Further, as described more fully below, the reflection signalmay be used to determine a fault type and/or a location of a fault.

In some embodiments, an output of a signal detector of a PHY may beoversampled (e.g., to increase resolution in the time domain). Morespecifically, for example, for a 40 nanosecond transmit pulse, an outputof a signal detector may be sampled every 10 nanoseconds.

Various embodiments of the present disclosure are now explained withreference to the accompanying drawings.

FIG. 1 is a block diagram of at least a portion of a network (e.g., awired local area network) 100, according to some embodiments. Morespecifically, network 100 may include a 10SPE network. Network 100includes a number of nodes (also referred to as “endpoints”) operablycoupled to a communication bus 104 (e.g., including one or more cables).More specifically, network 100 includes nodes 102_1, 102_2, 102_3,102_4, 102_5, and 102_6, generally nodes 102. Although network 100 isdepicted as having six nodes, the disclosure is not so limited, and anetwork may include more than six nodes (e.g., eight nodes, ten nodes,twelve nodes, or more) or less than six nodes (e.g., five nodes, threenodes, or two nodes).

Each node 102_1, 102_2, 102_3, 102_4, 102_5, and 102_6 is configured tocommunicate via communication bus 104, which may include, or be, ashared bus (e.g., a single twisted pair). As used herein, the term“shared bus” refers to a wired transmission medium, such as a singletwisted pair, that conducts both transmit signals and receive signalsover the same conductive structure (e.g., one or more cables).

In at least some embodiments, network 100 may be used in an automotiveenvironment. More specifically, by way of non-limiting example, network100 may be configured to connect one or more of nodes 102 to othernodes, a computer, and/or controller (e.g., within a vehicle). In thisexample, each node 102 of network 100 may include, for example, anamplifier, a microphone, an antenna, a speaker, and/or a sensor, withoutlimitation.

FIG. 2 depicts an example network segment 101 including a node 102(e.g., node 102_1, node 102_2, node 102_3, node 102_4, node 102_5, ornode 102_6) coupled to communication bus 104. As shown in FIG. 2, node102 includes a physical layer (PHY) 106 operably coupled to a mediaaccess control (MAC) layer 108. PHY 106 may be configured to serve as aninterface for a physical connection between MAC 108 and a network ordevice via communication bus 104. In some embodiments, PHY 106 includesat least a portion of Ethernet physical layer circuitry. As describedmore fully below, a PHY (e.g., PHY 106) may include a transceiver havingtransmit circuitry and receive circuitry, and detection circuitryincluding at least one signal detector.

FIG. 3A includes a timing diagram 300 depicting a transmit pulse signal302, a reflection signal 304, and an observed signal 306. For example,transmit pulse signal 302 represents a signal transmitted from a PHY(e.g., of node 102_1 of FIG. 1), reflection signal 304 represents areflection of transmit pulse signal 302, and observed signal 306represents a signal observed at the transmitting PHY (e.g., of node102_1 of FIG. 1), i.e., in response to transmit pulse signal 302.

As will be appreciated, observed signal 306 includes both transmit pulsesignal 302 and reflection signal 304. According to various embodiments,as described more fully below, information about a reflection signal(e.g., reflection signal 304) may be derived from an observed signal(e.g., observed signal 306). In other words, it may be possible todetermine information about reflection signal 304 (e.g., a shape, aphase, and/or an orientation (i.e., either positive or negative)) basedon information about transmit pulse signal 302 and observed signal 306.Further, based on information about reflection signal 304 (e.g., phaseand/or orientation), a type of a cable fault (i.e., a fault with one ormore cables of communication bus 104 of FIGS. 1 and 2) may bedetermined. In the example shown in FIG. 3A, transmit pulse signal 302and reflection signal 304 are both positive and include similar pulseshapes, which is indicative of an “open” fault.

With continued reference to timing diagram 300, a location of a cablefault may be determined based on a time duration 310 between a risingedge of transmit pulse signal 302 and a rising edge of reflection signal304. More specifically, for example, it may be determined that timeduration 310 is equal to 20 nanoseconds, and assuming 5nanoseconds/meter, it may be determined that the cable fault is about 2meters away from the associated node, e.g., node 102_1. An examplemethod of determining a location of a cable fault will be describedbelow with reference to FIGS. 4A and 4B.

In some embodiments, determining a location of a cable fault may requireinformation from more than one node of a network. More specifically,each node of a number of nodes of a network may transmit a signal, andeach node may determine a reflection signal (i.e., based on atransmitted pulse and an observed signal). Further, using timinginformation from each node (i.e., a time duration between a transmittedsignal and a reflection signal), a location of a cable fault (i.e., oncommunication bus 104; see FIG. 1 or FIG. 2) may be determined.

FIG. 3B depicts another timing diagram 350 including a transmit pulsesignal 352, a reflection signal 354, and an observed signal 356. Forexample, transmit pulse signal 352 represents a signal transmitted froma PHY (e.g., of node 102_1 of FIG. 1), reflection signal 354 representsa reflection of transmit pulse signal 352, and observed signal 356represents a signal observed at the transmitting PHY (e.g., of node102_1 of FIG. 1) , i.e., in response to transmit pulse signal 352.

As will be appreciated, observed signal 356 includes both transmit pulsesignal 352 and reflection signal 354. According to various embodiments,as described more fully below, information about reflection signal 354may be derived from observed signal 356. In other words, it may bepossible to determine e.g., a shape, a phase, and/or an orientation(i.e., either positive or negative) of reflection signal 354 based oninformation about transmit pulse signal 352 and observed signal 356.Further, based on reflection signal 354 (e.g., phase and/or orientation)relative to transmit pulse signal 352, a type of a cable fault may bedetermined. In the example shown in FIG. 3B, which is indicative of a“short” fault, transmit pulse signal 352 and reflection signal 354include similar shapes, but one is positive and one is negative.Further, a location of the fault may be determined based on timeduration 360 between a rising edge of transmit pulse signal 352 and afalling edge of reflection signal 354.

With reference to a timing diagram 370 shown in FIG. 3C, it is notedthat if an observed signal 376 includes the same shape, amplitude, andorientation of a transmit pulse signal 372 (i.e., at each samplingtime), a reflection signal may not exist, and thus it may be determinedthat a network (e.g., network 100 of FIG. 1) does not include a cablefault (e.g., a properly terminated or normal condition).

FIG. 4A depicts a timing diagram 400 including a transmit pulse signal402, a reflection signal 404, and an observed signal 406, observed atthe node with transmitted transmit pulse signal 402. For example,transmit pulse signal 402 represents a signal transmitted from a PHY(e.g., of node 102 of FIG. 2), reflection signal 404 represents areflection of transmit pulse signal 402, and observed signal 406represents a signal observed at the transmitting PHY (e.g., of node 102of FIG. 2). FIG. 4A further depicts a first (e.g., high) threshold value408, a second (e.g., normal) threshold value 410, and a third (e.g.,low) threshold value 412.

FIG. 4A further depicts a matrix 420 including a number of vectorsincluding a vector a[n], a vector b[n], a vector c[n], a vector t[n],and a vector r[n]. Each column of matrix 420 is associated with asampling time T1-T8, and each vector (i.e., a[n], b[n], c[n], t[n], andr[n]) includes an element n for each sampling time. As shown in FIG. 4A,a width of transmit pulse signal 402 is such that it is sampled fourtimes at the sampling rate. In other words, transmit pulse signal 402includes four sampling times (i.e., T1-T4). More specifically, forexample, transmit pulse signal 402 may include a pulse width of 40nanoseconds, and may be sampled at 10 nanosecond intervals.

In this example, vector a[n] is associated with observed signal 406relative to first threshold value 408, vector b[n] is associated withobserved signal 406 relative to second threshold value 410, and vectorc[n] is associated with observed signal 406 relative to third thresholdvalue 412. Further, vector t[n] is associated with transmit pulse signal402, and vector r[n] is associated with reflection signal 404. Asdescribed more fully below, each element n of each vector may be set toa logic value (e.g., either a 0 or a 1 or a 0 and a 2) depending on acomparison of an associated sample of observed signal 406 to therespective threshold value. The values of t[n] are determined based onthe status of the transmitted signal (e.g., “1” for high, and “0” forlow). More specifically, if transmit pulse signal 402 is a positivepulse, each element of vector t[n] will be a “1” for each sampling timeof transmit pulse signal 402. Further, if transmit pulse signal 402 is anegative pulse, each element of vector t[n] will be a “1” for eachsampling time of transmit pulse signal 402. The values of r[n], whichwill either be 0, 1, or −1, are determined responsive to equation (1)detailed below.

According to various embodiments, an example operation will now bedescribed with reference to FIG. 4A. In this example, first thresholdvalue 408 may be set, transmit pulse signal 402 may be transmitted and,for each sampling time of a number of sample times (e.g., T1-T8),observed signal 406 may be sampled and compared to first threshold value408 to generate an vector of elements a[n] for the observed signal 406.More specifically, a signal detector (e.g., a signal detector 600 ofFIG. 6) may be programmed with first threshold value 408 (e.g., between1× and 2×, wherein X is an amplitude of transmit pulse signal 402), thetransmit pulse signal 402 may be transmitted, and an output of thesignal detector 600 may be sampled (i.e., at each sampling time), andpossibly recorded.

More specifically, for vector a[n], at the first two sampling times T1and T2, the samples of observed signal 406 are not greater than firstthreshold value 408, and thus the values of a[1] and a[2] are each 0.Further, for the next two sampling times (i.e., T3 and T4), the samplesof observed signal 406 are greater than first threshold value 408, andthus, the values of a[3] and a[4] are each 1. For the remaining samplingtimes (i.e., T5-T8), the samples of observed signal 406 are not greaterthan first threshold value 408, and thus the values of a[5], a[6], a[7],and a[8] are each 0.

Continuing with this example, second threshold value 410 may be set,transmit pulse signal 402 may be transmitted again, and, for eachsampling time of a number of sample times (e.g., T1-T8), observed signal406 may be sampled and compared to second threshold value 410 togenerate a vector of elements b[n] for the observed signal. Morespecifically, signal detector 600 of FIG. 6 may be programmed with thesecond threshold value (e.g., between 0 and X, wherein X is an amplitudeof transmit pulse signal 402), transmit pulse signal 402 may betransmitted, and an output of signal detector 600 may be sampled (i.e.,at each sampling time), and possibly recorded.

For b[n], at the first six sampling times T1-T6, the samples of observedsignal 406 are greater than second threshold value 410, and thus, thevalues of b[1]-b[6] are each 1. Further, for the next two sampling times(i.e., T7 and T8), the samples of observed signal 406 are not greaterthan second threshold value 410, and thus the values of b[7] and b[8]are each 0.

Continuing with this example, third threshold value 412 may be set,transmit pulse signal 402 may be transmitted again, and, for eachsampling time of a number of sample times (e.g., T1-T8), observed signal406 may be sampled and compared to third threshold value 412 to generatean array of elements c[n] for observed signal 406. More specifically,signal detector 600 may be programmed with third threshold value 412(e.g., between 0 and −X, wherein X is an amplitude of the pulse),transmit pulse signal 402 may be transmitted, and an output of signaldetector 600 may be sampled (i.e., at each sampling time), and possiblyrecorded.

For c[n], at each sampling time T1-T8, the samples of observed signal406 are not less than third threshold value 412, and thus, the values ofc[1]-b[7] are each 0.

Further, in this example, the values of transmit pulse signal 402 (i.e.,for each threshold value setting) at sampling times T1-T8 is 1, 1, 1, 1,0, 0, 0, 0 (i.e., t[n]=(1, 1, 1, 1, 0, 0, 0, 0)), based on the settingof the transmitter, i.e., “1” when the transmitter is transmitting ahigh signal, and “0” otherwise. Further, a value of a reflection arrayr[n] at each sampling time (e.g., along columns of matrix 420) may bedetermined via the following equation:

r[n]=a[n]+b[n]−c[n]−t[n].   (1)

As will be appreciated, based on equation (1), at each sampling time,r[n] is equal to the element of vector a[n] plus the element of vectorb[n] minus the element of vector c[n] minus the element of vector t[n].Based on equation (1) above, array r[n]=(0 0, +1, +1, +1, +1, 0, 0).According to various embodiments, because array r[n] includes a positivevalue, an “open” fault exists.

Another example operation will now be described with reference to FIG.4B. FIG. 4B is a timing diagram 450 depicting a transmit pulse signal452, a reflection signal 454, and an observed signal 456, observed atthe node with transmitted transmit pulse signal 452. For example,transmit pulse signal 452 represents a signal transmitted from a PHY(e.g., of node 102 of FIG. 2), reflection signal 454 represents areflection of transmit pulse signal 452, and observed signal 456represents a signal observed at the PHY (e.g., of node 102 of FIG. 2).FIG. 4B further depicts a first (e.g., high) threshold value 458, asecond (e.g., normal) threshold value 460, and a third (e.g., low)threshold value 462.

FIG. 4B further depicts a matrix 470 including a number arrays includingan array a[n], an array b[n], an array c[n], an array t[n], and an arrayr[n]. Each column of matrix 470 is associated with a sampling timeT1-T8, and each array (i.e., a[n], b[n], c[n], t[n], and r[n]) includesan element n for each sampling time. Similar to transmit pulse signal402 of FIG. 4A, transmit pulse signal 452 is 4X a sampling rate. Inother words, transmit pulse signal 452 is sampled 4 times over thelength of transmit pulse signal 452 (i.e., T1-T4).

In this example, array a[n] is associated with observed signal 456relative to first threshold value 458, array b[n] is associated withobserved signal 456 relative to second threshold value 460, and arrayc[n] is associated with observed signal 456 relative to third thresholdvalue 462. Further, array t[n] is associated with transmit pulse signal452, and array r[n] is associated with reflection signal 454. Asdescribed more fully below, each element n of each array may be set toeither a 0 or a 1 depending on a comparison of an associated sample ofobserved signal 456 to a respective threshold value. The values of t[n]are determined based on the status of the transmitted signal, i.e., “1”for high, and “0” for low. The values of r[n] are determined responsiveto equation (1) above.

Similar to as described above with reference to FIG. 4A, respectivethreshold values may be set, transmit pulse signal 452 may betransmitted and, for each sampling time of a number of sample times, anobserved signal may be compared to the threshold value to generate anarray of elements n for the observed signal relative to the thresholdvalue. This may be repeated for one or more additional threshold values.

For the example shown in FIG. 4B, for array a[n], at each sampling timeT1-T8, the samples of observed signal 456 are not greater than firstthreshold value 458, and thus the values of a[1]-a[8] are each 0. Forb[n], at the first two sampling times T1 and T2, the samples of observedsignal 456 are greater than second threshold value 460, and thus, thevalues of b[1] and b[2] are each 1. Further, for the next six samplingtimes T3-T8, the samples of observed signal 456 are not greater thansecond threshold value 460, and thus the values of b[3]-b[8] are each 0.

For c[n], for the first four sampling times T1-T4, the samples ofobserved signal 456 are not less than third threshold value 462, andthus, the values of c[1]-c[4] are each 0. For the next two samplingtimes T5 and T6, the samples of observed signal 456 are less than thirdthreshold value 462, and thus, the values of c[5] and c[6] are each 1.For the next two sampling times T7 and T8, the samples of observedsignal 456 are not less than third threshold value 462, and thus, thevalues of c[7] and c[8] are each 0.

Further, in this example, the values of transmit pulse signal 452transmitted at sampling times T1-T8 may be 1, 1, 1, 1, 0, 0, 0, 0 (i.e.,t[n]=(1, 1, 1, 1, 0, 0, 0, 0)). Based on equation (1) above, arrayr[n]=(0, 0, −1, −1, −1, −1, 0, 0). According to various embodiments,because array r[n] includes a negative value, a “short” fault exists. Itis noted that if array r[n] included all zeros, a reflection was notreceived, and thus it may be determined that a cable fault does notexist.

Further, a fault position may be determined based on the first non-zeroelement in array r[n]. More specifically, in the example in which arrayr[n]=(0, 0, −1, −1, −1, −1, 0, 0), the first non-zero of array r[n] isat the third sampling time. Further, assuming each sampling time is 10nanoseconds, and further assuming 5 nanoseconds/meter, it may bedetermined that the cable fault is about 3 meters away from theassociated node.

FIG. 5 illustrates an example PHY 500, in accordance to variousembodiments of the disclosure. PHY 500 is provided as an example PHYconfiguration that may be used for carrying out various embodimentsdisclosed herein; however, the disclosure is not limited to any specificPHY configuration, and other configurations may be within the scope ofthe disclosure.

For example, PHY 106 of FIG. 2 may include PHY 500. PHY 500 includesreceive and transmit circuitry 502, which may be coupled to acommunication bus 504 and a MAC (not shown in FIG. 5, e.g., MAC 108 ofFIG. 2). For example, communication bus 504 may include communicationbus 104 of FIG. 1 and FIG. 2. Communication bus 504, which may be usedfor both transmitting and receiving data, may include a single twistedpair (e.g., an Unshielded Twisted Pair, or UTP).

PHY 500 further includes a controller 506, which may include a signaldetector 508 and fault detection logic 510. As described more fullyherein, in response to a transmitted signal (i.e., a signal transmittedvia PHY 500, such as transmit pulse signal 302 of FIG. 3A or transmitpulse signal 352 of FIG. 3B), controller 506 may be configured to detectan amplitude of an observed signal at a number of samplings times. Morespecifically, as described above with reference to FIGS. 4A and 4B, theamplitude of the observed signal (e.g., observed signal 406 or observedsignal 456) at each sampling time may be used, along with the amplitudeof the transmit pulse signal at each sampling time, to determine if theobserved signal includes a reflection of the transmit pulse signal. PHY500 may further include a calibration unit 514 for programming signaldetector 508 with one or more threshold values.

Signal detector 508 may be configured to detect signals observed viacommunication bus 504. More specifically, a signal REC, which mayinclude a differential signal (e.g., signal RXP, RXN shown in FIG. 6)may be observed at signal detector 508 via communication bus 504. Foreach sampling time of a number of sampling times (e.g., T1-T8; see FIGS.4A and 4B), signal detector 508 may detect an amplitude of signal REC,compare the amplitude to a threshold value, and convey a signal det_out,which may be a logic value (e.g., 0 or 1) that is indicative of theamplitude of signal REC at a sampling time compared to the thresholdvalue. If, for a sampling time, the absolute value of the amplitude ofsignal REC is equal to or greater than the threshold value, signaldet_out may include a first logic value (e.g., a logic 1). If, for asampling time, the absolute value of the amplitude of signal REC is lessthan the threshold value, signal det_out may be a second, differentlogic value (e.g., a logic 0).

For example, for each sampling time of a number of sampling time, signaldet_out may be supplied to fault detection logic 510, which may storethe values of signal det_out. This may be repeated for each samplingtime to generate a vector of logic values (e.g., array a[n] of FIG. 4Aor FIG. 4B) for signal REC compared to the threshold value. The vectormay be stored in fault detection logic 510. This may be repeated foreach threshold value to generate additional vectors of logic values(e.g., array b[n] and c[n] of FIG. 4A or FIG. 4B), which may also bestored in fault detection logic 510. Moreover, according to someembodiment, vector t[n] may be determined based on information (e.g.,pulse width and/or amplitude) about a transmitted pulse signal, whereinthe information may be transmitted from receive and transmit circuitry502 to fault detection logic 510. Further, after generating arrays foreach threshold value, fault detection logic 510 may compute reflectionarray r[n] according to equation (1) provided above. Further, based onarray r[n], fault detection logic 510 may be configured to determine afault type (e.g., via a lookup table) and possibly a location of thefault (e.g., based on a first non-zero value of array r[n]). Also, faultdetection logic 510 may be configured to generate a signal FS indicativeof a fault, or lack thereof. For example, signal FS may be conveyed to aMAC (e.g., MAC 108 of FIG. 2) and/or one or more other nodes of anetwork.

In some embodiments, PHY 500 may also include a clock 515 (e.g., a 100MHz clock) for generating a clock signal, which may be conveyed to faultdetection logic 510, transmit and receive circuitry 502, and signaldetector 508. For example only, the clock signal may be used to triggersampling, clock sampling logic, and/or determine a time duration betweensignal transmission (e.g., a rising edge of a transmit pulse) andreception of a pulse (e.g., a rising edge of reflection signal).

It is noted that in some embodiments, at least some portions oftransmitter (e.g., a pulse shaper and/or a driver) and/or at least someportions of a receiver (e.g., a signal detector) may be in a chipseparate from a chip including signal detector 508 and fault detectionlogic 512.

FIG. 6 illustrates an example signal detector 600, according to variousembodiments of the disclosure. As illustrated, signal detector 600includes a comparator 602 configured, generally, to compare adifferential signal (i.e., a measured difference between the + and −inputs of comparator 602 shown in FIG. 2) to a threshold and convey anoutput signal, det_out in response to the comparison. During acontemplated operation of signal detector 600, differential inputs, +and − of comparator 602 may be operatively coupled to R×P and R×N,respectively.

At signal detector 600, the threshold may be tuned, during faultdetection, via a threshold value control signal, thrsh_cntl <X:0>,provided, for example, by calibration unit 514 of FIG. 5. Tuning duringfault detection is discussed in more detail, below.

In one or more embodiments, fault detection may be performed usingmultiple threshold values. More specifically, in at least one example,signal detector 600, and more specifically, comparator 602, mayprogrammed with a first threshold value for comparing an observed signalto the first threshold value to detect a high positive signal. Further,signal detector 600, and more specifically, comparator 602, mayprogrammed with a second threshold value for comparing an observedsignal to the second threshold value to detect a low positive signal.Further, signal detector 600, and more specifically, comparator 602, mayprogrammed with a third threshold value for comparing an observed signalto the third threshold value to detect a negative signal. In thisexample, for each sample period, if detector output signal det_outincludes a low potential signal, a state of the associated observedsignal at the sample period may be assigned a low value. Otherwise, ifdetector output signal det_out includes a high potential signal, thestate of the associated observed signal at the sample period may beassigned a high value. Using multiple thresholds for fault detection isdiscussed in more detail, below. Examples of using multiple thresholdsare discussed, below.

FIG. 7 is a flowchart of an example method 700 of determining a faultcondition in a network, such as a 10SPE network. Method 700 may bearranged in accordance with at least one embodiment described in thepresent disclosure. Method 700 may be performed, in some embodiments, bya device, system, or network, such as network 100 of FIG. 1, node 102 ofFIG. 2, PHY 500 of FIG. 5, signal detector 600 of FIG. 6, and/or one ormore of the components thereof, or another system or device. In theseand other embodiments, method 700 may be performed based on theexecution of instructions stored on one or more non-transitorycomputer-readable media. Although illustrated as discrete blocks,various blocks may be divided into additional blocks, combined intofewer blocks, or eliminated, depending on the desired implementation.

Method 700 may begin at block 702, wherein a comparator threshold is setaccording to first threshold value (e.g., for detecting high positivesignal samples). For example, the first threshold may be set to detect asignal that has an amplitude higher than an amplitude of a pulse signalof block 704.

At block 704, a pulse signal may be transmitted to a cable of a sharedbus, and method 700 may proceed to block 704. For example, PHY 106 ofFIG. 2 may transmit a pulse (e.g., a 40 nanosecond pulse, a 50nanosecond pulse, a 60 nanosecond pulse, without limitation) viacommunication bus 104, which includes the cable.

At block 706, a signal received by at the transmitter node responsive tothe transmitted pulse may be observed, and method 700 may proceed toblock 706. More specifically, for example, the signal may be observedvia one or more signal detectors (e.g., one or more of signal detectors600 of FIG. 6) of controller 506 of FIG. 5.

At block 708, the observed signal may be sampled and a set of samplesobtained, and method 700 may proceed to block 708. For example thesignal may be oversampled (e.g., the signal may be sampled every 6nanoseconds, 8 nanoseconds, 10 nanoseconds, without limitation).

At block 710, the comparator threshold is set according to a secondthreshold value (e.g., for detecting low positive signal samples), andthen blocks 704, 706, and 708 are repeated. For example, the secondthreshold may be set to detect a signal that has an amplitude greaterthan zero and less than an amplitude of the pulse signal of block 704.

At block 712, the comparator threshold is set according to a thirdthreshold value (e.g., for detecting negative signal samples), and thenblocks 704, 706, and 708 are repeated. For example, the third thresholdmay be set to detect a signal that has an amplitude less than zero andgreater than the negative of the amplitude of the pulse signal of block704.

After block 712, three sets of samples have been obtained.

At block 714, a fault condition of the cable may be determined based onthe transmitted pulse and on a state of samples of each set of obtainedsamples for the observed signals at a number of sampling times. Forexample, based on the transmitted pulse and the state of each sample ofthe observed signal, it may be determined that a fault condition of thecable includes one of an open fault, a closed fault, a mismatch, or nofault.

Notably, instead of programming and re-programming a comparatoraccording to first, second and third threshold values, in anotherembodiment a signal detector may include three comparators for signalthreshold detection, e.g., a first comparator configured to detect afirst threshold, a second comparator configured to detect a secondthreshold, and a third comparator configured to detect a thirdthreshold. In such an embodiment, three sets of samples may be obtainedfrom transmitting one pulsed signal and then processed as describedherein.

Modifications, additions, or omissions may be made to method 700 withoutdeparting from the scope of the present disclosure. For example, theoperations of method 700 may be implemented in differing order.Furthermore, the outlined operations and actions are only provided asexamples, and some of the operations and actions may be optional,combined into fewer operations and actions, or expanded into additionaloperations and actions without detracting from the essence of thedisclosed embodiment. For example, method 700 may include comparing eachsample of the observed signal to one or more threshold values todetermine states of each sample of the observed signal relative to theone or more threshold values. More specifically, method 700 may includecomparing each sample of the observed signal to a first threshold value,a second threshold value, and a third threshold value to determine astate of each sample of the observed signal relative to the firstthreshold value, the second threshold value, and the third thresholdvalue. Further, method 700 may include determining a value for eachstate of a reflection signal based on the transmitted pulse and thestates of each sample of the observed signal relative to the firstthreshold value, the second threshold value, and the third thresholdvalue.

Various embodiments of the present disclosure may be implemented is10SPE networks for various applications, such as automotive application,industrial applications, server backplanes, without limitation. Further,various embodiments of the disclosure may be applicable to building,elevators, lighting, industrial in-field, Internet of Things (TOT),without limitation.

As used in the present disclosure, the terms “module” or “component” mayrefer to specific hardware implementations configured to perform theactions of the module or component and/or software objects or softwareroutines that may be stored on and/or executed by general purposehardware (e.g., computer-readable media, processing devices, etc.) ofthe computing system. In some embodiments, the different components,modules, engines, and services described in the present disclosure maybe implemented as objects or processes that execute on the computingsystem (e.g., as separate threads). While some of the system and methodsdescribed in the present disclosure are generally described as beingimplemented in software (stored on and/or executed by general purposehardware), specific hardware implementations or a combination ofsoftware and specific hardware implementations are also possible andcontemplated.

Terms used in the present disclosure and especially in the appendedclaims (e.g., bodies of the appended claims) are generally intended as“open” terms (e.g., the term “including” should be interpreted as“including, but not limited to,” the term “having” should be interpretedas “having at least,” the term “includes” should be interpreted as“includes, but is not limited to,” etc.).

Additionally, if a specific number of an introduced claim recitation isintended, such an intent will be explicitly recited in the claim, and inthe absence of such recitation no such intent is present. For example,as an aid to understanding, the following appended claims may containusage of the introductory phrases “at least one” and “one or more” tointroduce claim recitations. However, the use of such phrases should notbe construed to imply that the introduction of a claim recitation by theindefinite articles “a” or “an” limits any particular claim containingsuch introduced claim recitation to embodiments containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should be interpreted to mean “at least one”or “one or more”); the same holds true for the use of definite articlesused to introduce claim recitations. “Based on” means “based, at leastin part, on.”

In addition, even if a specific number of an introduced claim recitationis explicitly recited, those skilled in the art will recognize that suchrecitation should be interpreted to mean at least the recited number(e.g., the bare recitation of “two recitations,” without othermodifiers, means at least two recitations, or two or more recitations).Furthermore, in those instances where a convention analogous to “atleast one of A, B, and C, etc.” or “one or more of A, B, and C, etc.” isused, in general such a construction is intended to include A alone, Balone, C alone, A and B together, A and C together, B and C together, orA, B, and C together, etc.

Further, any disjunctive word or phrase presenting two or morealternative terms, whether in the description, claims, or drawings,should be understood to contemplate the possibilities of including oneof the terms, either of the terms, or both terms. For example, thephrase “A or B” should be understood to include the possibilities of “A”or “B” or “A and B.”

Additional non-limiting embodiments of the disclosure include:

Embodiment 1: A method of determining a fault condition of a cable of ashared bus, comprising: transmitting one or more pulse signals from anode to a cable of a shared bus; observing one or more signals receivedat the node in response to the pulse; sampling the one or more observedsignals; and determining a fault condition of the cable based on the oneor more transmitted pulses and on an amplitude of each sample of anumber of samples of the one or more observed signals.

Embodiment 2: The method according to Embodiment 1, wherein determiningthe fault condition comprises determining values of one or morereflection signals.

Embodiment 3: The method according to any of Embodiments 1 and 2,wherein determining the value of the reflection signal comprises:comparing an amplitude of each sample of the one or more observedsignals to each of a first threshold value, a second threshold value anda third threshold value, wherein the first and second threshold valuesare positive values, and the first threshold value is greater than thesecond threshold value, and the third threshold value is negative; anddetermining the values of the one or more reflection signals based onthe comparison of the amplitude of the samples of the one or moreobserved signals to each of the first threshold value, the secondthreshold value, and the third threshold value.

Embodiment 4: The method according to any of Embodiments 1 through 3,further comprising: for each of the number of samples of the one or moreobserved signals: comparing the one or more observed signals to a firstthreshold value to determine a first value of a sample of the one ormore observed signals relative to the first threshold value; comparingthe one or more observed signals to a second threshold value todetermine a second value of the sample of the one or more observedsignals relative to the second threshold value; and comparing the one ormore observed signals to a third threshold value to determine a thirdvalue of the sample of the one or more observed signals relative to thethird threshold value.

Embodiment 5: The method according to any of Embodiments 1 through 4,wherein determining the fault condition of the cable comprisingdetermining the fault condition of the cable based on the first value,second value, and third value of each sample of the one or more observedsignals.

Embodiment 6: The method according to any of Embodiments 1 through 5,wherein said sampling is every 10 nanoseconds.

Embodiment 7: A method of detecting a cable fault, comprising:transmitting a first pulse signal from a node to a cable of a sharedbus; observing a first signal received at the node in response to thetransmitted first pulse signal; determining a state of the observedfirst signal at each sampling time of a number of sampling times of theobserved first signal based on a comparison of the observed first signalat each sampling time to a first threshold value; transmitting a secondpulse signal from the node to the cable of the shared bus; observing asecond signal received at the node in response to the transmitted secondpulse signal; determining a state of the observed second signal at eachsampling time of a number of sampling times of the observed secondsignal based on a comparison of the observed second signal at eachsampling time of the number of sampling times of the observed secondsignal to at a second threshold value; and transmitting a third pulsesignal from the node to the cable of the shared bus; observing a thirdsignal received at the node in response to the transmitted third pulsesignal; determining a state of the observed third signal at eachsampling time of a number of sampling times of the observed third signalbased on a comparison of the observed third signal at each sampling timeof the number of sampling times of the observed third signal to a thirdthreshold value; and determining a fault condition based on the state ofthe observed first signal at each sampling time of the number ofsampling times of the observed first signal, the state of the observedsecond signal at each sampling time of the number of sampling times ofthe observed second signal, and the state of the observed third signalat each sampling time of the number of sampling times of the observedthird signal.

Embodiment 8: The method according to Embodiment 7, wherein determiningthe fault condition comprises determining a state of a reflection signalat each sampling time of the number of sampling times based on the stateof the observed first signal at each sampling time of the number ofsampling times, the state of the observed second signal at each samplingtime of the number of sampling times, and the state of the observedthird signal at each sampling time of the number of sampling times.

Embodiment 9: The method according to any of Embodiments 7 and 8,wherein determining the state of the first signal at each sampling timeof the number of sampling times comprises comparing the first signal ateach sampling time to the first threshold value comprising a firstpositive value.

Embodiment 10: The method according to any of Embodiments 7 through 9,wherein determining the state of the second signal at each sampling timeof the number of sampling times comprises comparing a second signal ateach sampling time to the second threshold value comprising a second,lower positive value.

Embodiment 11: The method according to any of Embodiments 7 through 10,wherein determining the state of the third signal at each sampling timeof the number of sampling times comprises comparing the third signal ateach sampling time to a third threshold value comprising a negativevalue.

Embodiment 12: A method of detecting a fault in a cable of a network,the method comprising: transmitting a pulse signal from a node to acable of a shared bus of the network; observing a signal received at thenode in response to the pulse; and determining a fault condition of thecable based on the one or more observed signals.

Embodiment 13: The method according to Embodiment 12, whereindetermining the fault condition comprises: determining an amplitude areflection signal based on the pulse and the one or more observedsignals; and determining the fault condition based on the reflectionsignal.

Embodiment 14: The method according to any of Embodiments 12 and 13,further comprising determining a location of a fault condition based onthe reflection signal.

Embodiment 15: The method according to any of Embodiments 12 through 14,wherein determining the fault condition comprises one of detecting anopen fault condition and a short fault condition.

Embodiment 16: The method according to any of Embodiments 12 through 15,wherein observing the signal generated in response to the pulsecomprises observing the signal at a signal detector of a physical layer(PHY) of the network.

Embodiment 17: The method according to any of Embodiments 12 through 16,further comprising at least one of: programming the signal detector witha first threshold value; programming the signal detector with a secondthreshold value, the second threshold value being a positive value lessthan the first threshold value; and programming the signal detector witha third threshold value, the third threshold value being less than anegative value.

Embodiment 18: A single-pair Ethernet physical layer (PHY), comprising:a transmitter configured to transmit at least one pulse signal to acable of a shared bus; a receiver configured to observe at least onesecond signal received in response to the at least one transmitted pulsesignal; and a signal detector configured to: compare an amplitude ofeach sample of the at least one second signal to at least one thresholdvalue; and generate a detector output signal for each sample of the atleast one second signal based on the comparison of the amplitude of eachsample of the at least one second signal to the at least one threshold;and fault detection logic coupled to the signal detector and configuredto: receive the detector output signal for each sample of the at leastone second signal; and determine a fault condition of the cable based onthe at least one transmitted pulse signal and on an amplitude of eachsample of a number of the samples of the at least one second signal.

Embodiment 19: The PHY according to Embodiment 18, wherein the at leasta second signal comprises a second signal, a third signal, and a fourthsignal, wherein the signal detector is configured to: compare anamplitude of each sample of the second signal to a first positivethreshold value of the at least one threshold value; compare anamplitude of each sample of the third signal to a second, lower positivethreshold value of the at least one threshold value; and compare anamplitude of each sample of the fourth signal to a third negativethreshold value of the at least one threshold value.

Embodiment 20: The PHY according to any of Embodiments 18 and 19,wherein the fault detection logic is configured to determine the faultcondition of the cable based on the at least one transmitted pulsesignal, the amplitude of each sample of the second signal compared tothe first positive threshold value, the amplitude of each sample of thethird signal compared to the second, lower positive threshold value, andthe amplitude of each sample of the fourth signal to the third negativethreshold value.

Embodiment 21: The PHY according to any of Embodiments 18 through 20,wherein the signal detector comprises one or more comparators.

Embodiment 22: The PHY according to any of Embodiments 18 through 21,wherein the one or more comparators comprise one re-programmablecomparator.

Embodiment 23: The PHY according to any of Embodiments 18 through 22,wherein the one or more comparators comprise three comparators.

While the present disclosure has been described herein with respect tocertain illustrated embodiments, those of ordinary skill in the art willrecognize and appreciate that the present invention is not so limited.Rather, many additions, deletions, and modifications to the illustratedand described embodiments may be made without departing from the scopeof the invention as hereinafter claimed along with their legalequivalents. In addition, features from one embodiment may be combinedwith features of another embodiment while still being encompassed withinthe scope of the invention as contemplated by the inventor.

1. (canceled)
 2. A method, comprising: transmitting one or more pulsesignals from a node to a cable of a shared bus; sampling one or moresignals received at the node in response to the one or more pulsesignals; and determining a fault condition of the cable based on the oneor more pulse signals and a number of samples of the one or moresignals.
 3. The method of claim 2, wherein determining the faultcondition comprises determining values of one or more reflectionsignals.
 4. The method of claim 3, wherein determining the values of theone or more reflection signals comprises: comparing an amplitude of eachsample of the one or more signals to each of a first threshold value, asecond threshold value and a third threshold value; and determining thevalues of the one or more reflection signals based on the comparison ofthe amplitude of each sample of the one or more signals to each of thefirst threshold value, the second threshold value, and the thirdthreshold value.
 5. The method of claim 2, further comprising: for eachof the number of samples of the one or more signals: comparing the oneor more signals to a first threshold value to determine a first value ofa sample of the one or more signals relative to the first thresholdvalue; comparing the one or more signals to a second threshold value todetermine a second value of the sample of the one or more signalsrelative to the second threshold value; and comparing the one or moresignals to a third threshold value to determine a third value of thesample of the one or more signals relative to the third threshold value.6. The method of claim 5, wherein determining the fault condition of thecable comprising determining the fault condition of the cable based onthe first value, second value, and third value of each sample of the oneor more signals.
 7. The method of claim 2, wherein sampling comprisessampling every 10 nanoseconds.
 8. The method of claim 2, whereintransmitting the one or more pulse signals from the node to the cable ofthe shared bus comprises transmitting the one or more pulse signals fromthe node to the cable of the shared bus of a 10SPE network.
 9. Themethod of claim 2, wherein transmitting the one or more pulse signalsfrom the node to the cable of the shared bus comprises transmitting theone or more pulse signals from the node to the cable of the shared busof a vehicle communication network.
 10. A method, comprising:transmitting a pulse signal from a node to a cable of a shared bus of anetwork; observing a signal received at the node in response to thepulse signal; and determining a fault condition of the cable based onthe observed signal.
 11. The method of claim 10, wherein determining thefault condition comprises: determining an amplitude of a reflectionsignal based on the pulse signal and the observed signal; anddetermining the fault condition based on the reflection signal.
 12. Themethod of claim 11, further comprising determining a location of a faultcondition based on the reflection signal.
 13. The method of claim 10,wherein determining the fault condition comprises detecting either anopen fault condition or a short fault condition.
 14. The method of claim10, wherein observing the signal received at the node comprisesobserving the signal at a signal detector of a physical layer (PHY) ofthe network.
 15. The method of claim 14, further comprising at least oneof: programming the signal detector with a first threshold value;programming the signal detector with a second threshold value, thesecond threshold value being less than the first threshold value; orprogramming the signal detector with a third threshold value, the thirdthreshold value being less than a negative value.
 16. A device,comprising: a transmitter configured to transmit at least one pulsesignal to a cable of a shared bus; a receiver configured to observe atleast one second signal received in response to the at least one pulsesignal; and circuitry configured to: compare an amplitude of each sampleof the at least one second signal to at least one threshold value; andgenerate a detector output signal for each sample of the at least onesecond signal based on the comparison of the amplitude of each sample ofthe at least one second signal to the at least one threshold value; andreceive the detector output signal for each sample of the at least onesecond signal; and determine a fault condition of the cable based on theat least one pulse signal and an amplitude of each sample of a number ofthe samples of the at least one second signal.
 17. The device of claim16, wherein the at least a second signal comprises a second signal, athird signal, and a fourth signal, wherein the circuitry is configuredto: compare an amplitude of each sample of the second signal to a firstthreshold value of the at least one threshold value; compare anamplitude of each sample of the third signal to a second, lowerthreshold value of the at least one threshold value; and compare anamplitude of each sample of the fourth signal to a third negativethreshold value of the at least one threshold value.
 18. The device ofclaim 17, wherein the circuitry is configured to determine the faultcondition of the cable based on the at least one pulse signal, theamplitude of each sample of the second signal compared to the firstthreshold value, the amplitude of each sample of the third signalcompared to the second, lower threshold value, and the amplitude of eachsample of the fourth signal to the third negative threshold value. 19.The device of claim 18, wherein the circuitry comprises one or morecomparators.
 20. The device of claim 19, wherein the one or morecomparators comprise a re-programmable comparator.
 21. The device ofclaim 19, wherein the one or more comparators comprise threecomparators.